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Research
Simplified Predictive Nomogram for Postprostatectomy Patients Treated with High-dose Salvage Intensity Modulated Radiation Therapy
Jason Chia-Hsien Cheng
National Taiwan University
Corresponding Author
ORCiD: https://orcid.org/0000-0002-2007-0220
License:
This work is licensed under a CC BY 4.0 License. Read Full License
Purpose:
The role of salvage radiotherapy (RT) is established in prostate cancer patients undergoing radical prostatectomy (RP) with biochemical failure (BCF). Intensity modulated RT (IMRT) is adapted for post-RP treatment. This study aimed to investigate the prognostic factors and develop a nomogram to predict biochemical control in patients treated with exclusively salvage high-dose IMRT for post-RP BCF.
Materials and Methods:
One hundred and eleven patients underwent post-RP IMRT, and 92 patients were enrolled after excluding patients with adjuvant RT or lymph node metastasis on RP. Fifty-two percent of patients had androgen-deprivation therapy (ADT). Moreover, 20% and 34% had pathological T3a and T3b disease, respectively, and 70% had positive surgical margins. The median dose of IMRT was 70 Gy to the prostatic and seminal vesicle bed. Using multivariable Cox regression analysis, a nomogram model was generated to predict the probability of BCF after salvage IMRT.
Results:
The 5-year BCF-free survival (BFFS), metastasis-free survival (MFS), and overall survival (OS) after salvage IMRT were 56%, 89%, and 88%, respectively. Post-RP prostate-specific antigen (PSA) nadir >0.1 ng/ml (p=0.004), PSA >0.5 ng/ml at salvage IMRT (p=0.016), and Gleason score ≥8 (p=0.013) were independent unfavorable prognostic factors for BFFS on multivariate analyses. The use of ADT, T3a/T3b disease, and positive surgical margins were not associated with BFFS. The predictions from the 3-factor nomogram (post-RP PSA nadir, pre-IMRT PSA, and Gleason score) appeared to be discriminative. The concordance index was 0.713, similar to 0.739 from the 7-factor nomogram with the addition of ADT, T3a/3b, positive margins, and IMRT dose ≥70 Gy.
Conclusion:
Salvage IMRT for post-RP BCF achieved a satisfactory outcome. The simplified 3-factor (post-RP PSA nadir, pre-IMRT PSA, and Gleason score) nomogram predicted biochemical control and demanded further validation.
Keywords
Prostate cancer, Radical prostatectomy, Biochemical failure, Intensity modulated radiation therapy, Nomogram
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This is a preprint. It has not completed peer review.
Research
Simplified Predictive Nomogram for Postprostatectomy Patients Treated with High-dose Salvage Intensity Modulated Radiation Therapy
Jason Chia-Hsien Cheng
National Taiwan University
Corresponding Author
ORCiD: https://orcid.org/0000-0002-2007-0220
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
History
CURRENT STATUS: Posted
Version 1
Posted 28 Sep, 2020
No community comments so far
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
Subject Areas
Oncology
License:
This work is licensed under a CC BY 4.0 License. Read Full License
Purpose:
The role of salvage radiotherapy (RT) is established in prostate cancer patients undergoing radical prostatectomy (RP) with biochemical failure (BCF). Intensity modulated RT (IMRT) is adapted for post-RP treatment. This study aimed to investigate the prognostic factors and develop a nomogram to predict biochemical control in patients treated with exclusively salvage high-dose IMRT for post-RP BCF.
Materials and Methods:
One hundred and eleven patients underwent post-RP IMRT, and 92 patients were enrolled after excluding patients with adjuvant RT or lymph node metastasis on RP. Fifty-two percent of patients had androgen-deprivation therapy (ADT). Moreover, 20% and 34% had pathological T3a and T3b disease, respectively, and 70% had positive surgical margins. The median dose of IMRT was 70 Gy to the prostatic and seminal vesicle bed. Using multivariable Cox regression analysis, a nomogram model was generated to predict the probability of BCF after salvage IMRT.
Results:
The 5-year BCF-free survival (BFFS), metastasis-free survival (MFS), and overall survival (OS) after salvage IMRT were 56%, 89%, and 88%, respectively. Post-RP prostate-specific antigen (PSA) nadir >0.1 ng/ml (p=0.004), PSA >0.5 ng/ml at salvage IMRT (p=0.016), and Gleason score ≥8 (p=0.013) were independent unfavorable prognostic factors for BFFS on multivariate analyses. The use of ADT, T3a/T3b disease, and positive surgical margins were not associated with BFFS. The predictions from the 3-factor nomogram (post-RP PSA nadir, pre-IMRT PSA, and Gleason score) appeared to be discriminative. The concordance index was 0.713, similar to 0.739 from the 7-factor nomogram with the addition of ADT, T3a/3b, positive margins, and IMRT dose ≥70 Gy.
Conclusion:
Salvage IMRT for post-RP BCF achieved a satisfactory outcome. The simplified 3-factor (post-RP PSA nadir, pre-IMRT PSA, and Gleason score) nomogram predicted biochemical control and demanded further validation.
Figure 1
Figure 2
Figure 3